The man who gunned down his romantic rival more than eight years ago has become a better person, but a Suffolk County judge conceded Thursday that he still deserves the maximum sentence.

Daniel Greenspan, 30, of Manhattan, may be studious and religious now, but he wasn’t on Jan. 31, 2009, when he shot Michael Sinclair, 32, on a West Babylon street.

For that, state Supreme Court Justice William Condon sentenced Greenspan to prison for 25 years to life for second-degree murder.

“To me, this was a premeditated and personal execution, and it doesn’t get any colder than that,” Condon said.

Greenspan, who was born Daniel Kraeger and later changed his last name first to Rivera and then to Greenspan, was convicted in March of having his girlfriend, Noriella Santos, lure Sinclair from Brooklyn to West Babylon. Prosecutors say Greenspan believed Santos had contracted genital herpes from Sinclair and passed it on to him.

Condon acknowledged letters from numerous rabbis who have been impressed by Greenspan’s devotion to his religion and Talmudic study.

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“I don’t think I’m sentencing Daniel Greenspan,” the judge said. “I’m sentencing Danny Rivera, the guy who pulled the trigger five times.”

Robert Sinclair of Manhattan said in court that the loss of his only child has been devastating to him and his wife. He said he is still astounded that his son, who never argued or confronted anyone, could be killed by someone he’d never met.

Sinclair said his wife had always been “the brightest person in the room,” but no more. “That person ceased to exist on the 31st of January,” he said.

She developed congestive heart failure within a few years of the murder, he said, prompting Condon to interject: “Her heart was broken.”

“That’s why no one’s seen her here” in court, Sinclair continued. “Me, I would pretend there was a reason to get out of bed every day.”

Assistant District Attorney Nancy Clifford contrasted the victim with Greenspan. She noted that Greenspan’s supporters cite his work ethic, but “we have no documentation that he’s ever had a job,” she said.

She said supporters describe Greenspan’s “high moral character,” ignoring his drug arrest with his father and extensive documentation of his domestic violence toward Santos, including arrests and hospital records.

Defense attorney Arthur Aidala of Manhattan said his client was never convicted of any other crime — and continues to proclaim his innocence in the killing.

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“He had problems, but he was never a stone-cold killer,” Aidala said. He said Santos — who pleaded guilty to second-degree attempted robbery for her role and likely will get probation — was the force behind the murder.